Meningitis is inflammation of an area between two of the three membranes--known as the meninges--covering the brain and spinal cord. Possible causes of meningitis include bacteria, fungi and parasites, but when a virus causes the condition doctors refer to it as viral meningitis. The National Institute of Neurological Disorders and Stroke notes that viral meningitis is milder but more common than bacterial meningitis and occurs through infection by many different viruses. Some of the viruses may also cause other diseases.
Enteroviruses
Enteroviruses, the most common cause of viral meningitis, include echoviruses, Coxsackie viruses, human enteroviruses 68 to 71, and polioviruses, according to Dr. Karen L. Roos, author of "Principles of Neurologic Infectious Diseases" and Professor of Neurology at the Indiana University School of Medicine. Infections caused by these viruses occur more often during the summer, and the most common transmission vector is oral contact with fecal matter, such as might occur with children who have not yet learned to follow proper hygiene practices. Infection can also occur when a caregiver changes an infected infant's diaper. Liquid expelled from the respiratory system when someone coughs or sneezes can also spread enteroviruses. The Centers for Disease Control and Prevention, also known as the CDC, points out that viral meningitis occurs in only a few of those people infected with enteroviruses.
Arboviruses and HIV
The Merck Manual lists arthropod-borne viruses, or arboviruses, and the human immunodeficiency virus, or HIV, as other common causes of viral meningitis. The bite of a tick or mosquito can cause infections by arboviruses. Dr. Roos notes that the infectious arboviruses include the St. Louis encephalitis virus, Colorado tick fever virus, La Crosse virus, western equine encephalitis virus, tick-borne encephalitis virus and West Nile virus. The HIV type1 virus can cause rapidly developing acute viral meningitis or longer-lasting chronic viral meningitis in the infected person.
Herpesviruses
The CDC notes that several different viruses from the herpesvirus family can cause viral meningitis. These include the varicella-zoster virus, the virus that causes chicken pox in children and shingles--also known as herpes zoster--in adults. The Epstein-Barr virus, which can also cause mononucleosis, and the herpes simplex viruses, which cause cold sores and genital herpes, can also cause viral meningitis. The Merck Manual notes that some people may develop benign recurrent lymphocytic meningitis, also known as Mollaret's meningitis, after exposure to genital herpes. Patient who later develop viral meningitis are often unaware of their previous exposure to herpes.
Lymphocytic Choriomeningitis Virus
Rare infections with the lymphocytic choriomeningitis virus can occur through contact with rodents, according to the CDC. Dr. Roos mentions that this might occur through contact with laboratory rodents or house mice.
Mumps Virus
Now rare in the United States because of widespread vaccination, the mumps virus can cause viral meningitis in an infected person, according to doctors at the Mayo Clinic.
References
- National Institute of Neurological Disorders and Stroke: Meningitis and Encephalitis Fact Sheet
- "Principles of Neurologic Infectious Diseases,"; Karen Roos, M.D.; 2004
- Centers for Disease Control and Prevention: Meningitis Questions & Answers
- The Merck Manual for Healthcare Professionals: Aseptic Meningitis
- The Mayo Clinic: Meningitis - Causes
